Circuit breaker



Oct. 31, 1939.' 1., s. JIACKSON 2,177,775

CIRCUIT BREAKER Filed July 25, 1936 7 2 Sheets-Sheet 1 INVENTOR J'b]??? 6. J'acfisorz.

7%- izzg ATTORNEY Oct. 31, 1 939. J JACKSQN 2,177,775

CIRCUIT BREAKER Filed July 25, 1936 2 Shoots-Shut 2 3/ VINVENTOR Jbfi) 6f Jzzci'sarz.

BY? J ATTORNEY/ Patented Oct. 31, 1939 2,177,775

I UNITED STATES. PATENT OFFICE CIRCUIT BREAKER John G. Jackson, Detroit, Mich., assignor to Square D Company, Detroit, Mich, a corporation of Michigan Application July 25, 1936, Serial No. 92,645

7 @laims. (Cl. 200-116) This invention relates to devices for making base for rectilinear movement at right angles to and breaking electric circuits and more particuthe back of the base. The front edge of the conlarly to electric circuit breakers automatically tact bar H is provided with a second shallow operable in response to current overload. notch it which interengages with a shallow notch One object of the present invention is the proin the shorter leg of the element l3 to limit the 5 vision of an electric circuit breaker supplying movement of and properly position the bar in p, plurality of branch circuits through circuit the automatically tripped position. A heavy controlling elements and operating the elements compression spring 65 biases the contact bar it to interrupt the current through all the branch against the stationary contact surface and in circuits in response to a current overload in any against a latching surface to be hereinafter de-= one of them. scribed. A fibre barrier plate i0 is disposed be- Another object of the present invention is to tween the arcing chamber 7 and the circuit provide a circuit breaker having a single switchbreaker mechanism and has a restricted slot 'ing member and supplying a plurality of branch at its back end closely receiving the contact 1 l5 circuits, with tripping elements individual to the bar it. 5

branch circuits, any one of which is operable to Upon a boss or projection 66 at the bottom of effect movement of the switching member to inthe base is rigidly secured an L shaped bracket. terrupt the current through all the branch cir- W as by means of studs l8. At a position beside cuits.- the element i3 is similarly mounted an L shaped 20 Further objects and features of the invention bracket it? as by means of stud 2|. Guided 20 will be readily apparent to those skilled in the within slots in these brackets I7 and i9 is an art from the following specifications and the apelongated tripping bar 22. An S shaped bracket pended drawings illustrating certain embodi- 23 is rigidly welded or otherwise secured to trip ments of the invention in which: bar 2'2 and is also guided within a slot in the 25 Figure 1 is a front elevational view of a cir-. bracket it so as to provide a three point guiding 25 cuit breaker assembly according to the present and supporting means for the tripping unit. A invention with the cover and operating handle compression spring 24, interposed between the of one unit removed to show internal parts. brackets ill and 23, biases the tripping unit into Figure 2 is a vertical sectional view on the line the latching position. To the bracket 23 is at- II-II of Figure 1. tached a latching portion. 25 which is curved 30 I Figure 3 is a view similar to Figure 2 but showoutwardly and upwardly to provide-for easy pasing the parts in automatically tripped position. sage of the latching end of the contact bar it in Figure 4 is a reduced detail sectional view on oving to resett ng D U The p bar 22 is the line IV-IV of Figure 2. provided with a plurality of elongated notches The circuit breaker as shown in Figure l em- 26 in which are disposed the movable ends of 35 bodies'two distinct and identical units l and 2, current responsive bimetallic members 21. mounted within an enclosing box 3. These units Upon side ledges 28 at the exterior of the cirare electrically distinct and are adapted for feedcuit breaker enclosure are mounted conducting ing through wires of opposite polarity to a plusupports 29 as by means of spun over portions of rality of branch circuits. Each of these units metallic inserts, not shown. These supports are 40 includes a generally-cup shaped base 4 having a generally L shaped and extend within the inledge 5 adjacent to one .end, upon which is rigidterior of the circuit breaker and are there pro- "is: secured a conducting connector plate 6 as by vided with central pressed outportions 3!, to means of a spun over portion of a metallic insert, which the fixed ends of the bimetallic members not shown. The connector 6 extends within an 27 are welded or otherwise rigidly secured. Be- 45 are chamber 1 beside the ledge 5 and" ere suptween the central portions 3| and the straight ports a stationary contact surface 8. ooperatportions of the supports 29 are disposed bridging ing with the stationary contact surface 8 is a portions 32 in which are threaded studs 33 bearmovable contact surface 9 mounted adjacent to ing against the pressed out portions 3| and pro= one end of a floating contact bar ll. The front viding adjusting means for the bimetallic mem- 50 edge of the contact bar II is provided with a' bers 2i. Flexible leads 34 are brazed or othernotch H which receives the upper edge of a slot wise secured to the contact bar H and to each of generally centrally disposed in an elongated leg the bimetallic members 21 thus placing each of on a generally U shaped element E3. The elethe bimetallic members 27 in series with the con- 5 ment i3 is suitably guided by projections on the tact bar ll.

An operating handle 35 is pivotally mounted on shaft 36- disposed within grooves 31 at the front edge of the base. This handle has an interior cam portion for moving the element l3 rectilinearly in response to rotary movement of the handle and this cam surface includes a fiat portion 38 forming a stable support for the manual disengaged position, and a resetting tip 39. A light spring 4| biases the handle for rotation'in a clockwise direction as shown. The circuit breaker enclosure is provided with a front metallic cover 42 which may be sealably secured to the base 4 and beneath the cover 2 is provided a thin fibre sheet 43 which mayv include a side portion 44 for sealing the side of the circuit breaker enclosure adjacent to the current responsive bimetallic members. a

The operations of the circuit breaker will now be described.

The incoming line to the circuit breaker is attached to a terminal connector on the conduct- -ing plate 6 and the current traverses the plate 6 to the stationary contact 8, movable contact 9, contactbar II and through the flexible leads 34 to the individual bimetallic members 21, and

thence through the individual conducting sup-.

. tact bar II and permitting the parts to assume the position shown in Figure 3 with the contact bar rotated to contact disengaged position under the bias of compression spring l5. As illustrated in Figure 3 it is the top bimetal which has carried the overload and which has efiected tripping of the circuit breaker. the fact that the length of the notches 26 is greater than the movement of the trip bar necessary to eflect tripping of the contact bar, movement of the trip bar by any one bimetal may be eilected independently of the other bimetals and that the warping bimetal does not have to bear the load of moving the bimetals which are unaffected. As the-compression spring [5 is considerably-stronger than the light handle spring 4|, in the automatically tripped position the element l3 has been moved forwardly and the op- To eilect resetting of the circuit breaker mechanism after an automatic trip, the operating handle is rotated clockwise until the resetting tip 39. has pushed the element I 3 far enough toward the back of the base to cause the latching end of the contact bar H to have moved back of the latching portion 25. When the handle is again moved to the on position, the parts will then assume their normal closed circuit position.

To effect manual separation of the contact surfaces 8 and 9, the handle is rotated in a clockwise direction until the flat surface 38 engages the front of the element iii. In this movement the contact bar will be rotated about its engagement withv the latching portion 25 andv a stable condition will be attained which the parts will maintain until the operating handle is again rotated into closed circuit position.

It is noted that due to With the circuit breaker as herein illustrated and described, it is possible to feed a plurality of branch circuits through individual tripping elements which may have widely different ratings and to interrupt the current through the circuit breaker upon the occurrence of an overload in any one of the branch circuits. All the branch circuits are controlled by a single switching member whose tripping unit is independently under the control of the individual tripping members in the branch circuits. It can readily be seen that this permits a very desirable economy in manufacture while maintaining independent protection of the branch circuits in accordance with their individual ratings.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited there- I to as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

I claim:

1. An electric circuit breaker for feeding a plurality of branch circuits comprising separable contacts adapted to interrupt the current through all the branch circuits, and a bimetallic element serially connected in each of the branch circuits, each of said elements having an independent rating in accordance with the individual branch circuit protection desired and each being independently movable in response to current overload in its individual branch circuit to eifect separation of said contacts and interruption of the current through all the branch circuits, and manual means for effecting separation of said contacts at will, said last mentioned means being operable to effect the manual switching operation without in any way afiecting the bimetallic elements.

2. An electric circuit breaker comprising relatively movable contacts, a switching member biased to move said contacts to separated position, a latch restraining such movement of said switching member, a plurality of bimetallic mem- -will effect the opening of the circuits through all said branches, latching means for maintaining said movable contact in engagement with said stationary contact, spring means biasing said latching means into restraining position, said bimetallic members being operatively connected to effect movement of said latching means against said spring means upon the flexing of a member due to the passage of an overload current therethrough, said latching means being releasable by such movement of any one bimetallic member independently of the other members, and manual means for efiecting movement of said movable contact at will and without disturbing said latching means or bimetallic members.

4, An electric circuit breaker for feeding a D111- rality of branch circuits comprising a stationary contact, a movable switching member having a contact surface thereon cooperating with said stationary contact to perform the switching opsaid contact surface into and out of engagement with said contact, a plurality of independent bimetallic members'connected in parallel to feed through said contact and contact surface to aplurality of independent branch circuits, each of said bimetallic members having a rating corresponding to the desired protection for the branch circuit fed therethrough, a common trip bar adapted to eifect movement of said latching means to releasing position, and means whereby each of said bimetallic members may effect movement of saidcommon trip bar to release the latching means upon the occurrence of an overgiad current in the branch circuit which it supes. Y

'5. An electric circuit breaker for feeding a plurality of branch circuits comprising a sealable enclosure, switching contacts within said enclosure, means biasing said switching contacts to separated position, a reciprocable latch bar within said enclosure having a latching surface thereon for restraining said contacts in engaged position, a plurality of independent terminals at the exterior of said enclosure and having connectors extending to the interior thereof, independent bimetallic members mounted on said connectors within the enclosure, means connecting said himetallic members in parallel with each other and in series with said switching contacts, and means connecting the free ends of said bimetallic members to said trip bar to efiect movement thereof in response to an overload current through any one bimetallic member.

6. an electric circuit breaker for feeding a plurality of branch circuits comprising a scalable enclosu e, a m n t m n at the ex erio o s d engaged position.

enclosure, a stationary contact within the enclosure and connected to said main terminal, a switching member having a contact surface cooperating with said stationary contact, means biasing said switching member to a position separating said contact surfacefrom said contact, latching means restraining said switching member in a position to permit engagement of said contact surface with said contact, a plurality of branch circuit terminals at the exterior of the enclosure, a plurality of individual bimetallic members within the enclosure, each connected to one of said branch circuit terminals, means connecting said bimetallic members in parallel to said switching member, and means for efiecting movement of said latching means to releasing position by any one of the bimetallic members in response to an overload current in the branch circuit which it supplies.

I; An electric circuit breaker for feeding a plurality of branch circuits comprising a sealable enclosure, a main terminal at the exterior of said enclosure, a stationary contact within the enclosure and connected to said main terminal, a switching member having a contact surface cooperating with said stationary contact, means biasing said switching member to a position separating said contact surface from said contact, latching means restraining said switchin ber in a position to permit engagement of said contact surface with said contact, a plurality of branch circuit terminals at the exterior of the enclosure, a plurality of individual bimetallic members within the enclosure, each connected to one of said branch circuit terminals, means circuit which it supplies, and manual means accessible at the exterior of the enclosure for effecting movement of said switching member at will to move the contact surface to engaged and dis- JQH G. JACKSON. 

